This invention relates to designs and methods for preventing, stopping or slowing myopia progression.
Myopia, also known as short-sightedness, is a refractive condition wherein the overall power of the eye is too high, or too strong, causing light from distant objects to focus in front of the retina. This is perceived by the viewer as blurring of distant objects, with the amount of blurring being related to the severity of the myopia. This condition is often first seen in childhood, and usually noticed at school age. A progression, or increase, in the severity of myopia, is usually seen in myopic cases until young adulthood.
U.S. Pat. No. 6,045,578 proposes methods of using on-axis longitudinal spherical aberration (LSA) in contact lens designs to attempt to halt myopia progression. The design approach suggested does not appear to address specific wavefront/refractive power characteristics of the individual eye/or group average data or changes in pupil size associated with close work.
U.S. Pat. No. 7,025,460 proposes methods of altering field curvature (off-axis focal point variation) to try to halt myopia progression. The mathematics behind this approach uses “extended conics” where the simple conic equations have even ordered polynomial terms added to them. These conic and polynomial terms are processed so that the contact lens surface shape of the proposed design produces the required amount of field curvature. This approach addresses off-axis design.
On-axis optical design of the lens does not appear to have been addressed. Pupil size and wavefront changes associated with near tasks were not addressed.
US 2003/0058404 and US 2008/0309882 proposes a method of measuring the wavefront of the eye and correcting the wavefront of the eye with a customized correction to slow myopia progression. This did not include measuring the wavefront for a near stimulus distance and does not appear to suggest considering the difference between the wavefront measured for a far stimulus and a near stimulus. Pupil size changes associated with near tasks were also not an aspect of the design process.
EP 1853961 proposes the measurement of the wavefront before and after near work. The changes in wavefront aberrations are then corrected with a custom contact lens. This does not include the difference in wavefront measured for a far and near stimulus as only the wavefront before and after near work are addressed. It does not consider the pupil size changes associated with near tasks in the design process. Group or population data to create a design to control eye growth are not included.
A more complete approach to slowing or stopping myopia progression is still desired. This is addressed in this specification.